Minimally invasive robotic surgical or telesurgical systems have been developed to increase a surgeon's dexterity and to avoid some of the limitations on traditional minimally invasive techniques. In telesurgery, the surgeon uses some form of remote control, e.g., a servomechanism or the like, to manipulate surgical instrument movements, rather than directly holding and moving the instruments by hand. In telesurgery systems, the surgeon can be provided with an image of the surgical site at the surgical workstation. While viewing a two or three dimensional image of the surgical site on a display, the surgeon performs the surgical procedures on the patient by manipulating master control devices, which in turn control motion of the servomechanically operated instruments.
In robotically-assisted surgery, the surgeon typically operates a master controller to control the motion of surgical instruments at the surgical site from a location that may be remote from the patient (e.g., across the operating room, in a different room, or a completely different building from the patient). The master controller usually includes one or more hand input devices, such as hand-held wrist gimbals, joysticks, exoskeletal gloves or the like, which are operatively coupled to the surgical instruments that are releasably coupled to a patient side surgical manipulator (“the slave”). The master controller controls the instruments' position, orientation, and articulation at the surgical site. The slave is an electro-mechanical assembly which includes a plurality of arms, joints, linkages, servo motors, etc., that are connected together to support and control the surgical instruments. In a surgical procedure, the surgical instruments (including an endoscope) may be introduced directly into an open surgical site or more typically through trocar sleeves into a body cavity. Depending on a surgical procedure, there are available a variety of surgical instruments, such as tissue graspers, needle drivers, electrosurgical cautery probes, etc., to perform various functions for the surgeon, e.g., holding or driving a needle, suturing, grasping a blood vessel, or dissecting, cauterizing or coagulating tissue.
A surgical manipulator assembly may be said to be divided into three main components that include a non-sterile drive and control component, a sterilizable end effector or surgical tool/instrument, and an intermediate connector component. The intermediate connector component includes mechanical elements for coupling the surgical tool with the drive and control component, and for transferring motion from the drive component to the surgical tool. Cables (also referred to as wire rope) and pulleys in conjunction with motors have been used to actuate carriages, the surgical instrument, and other apparatus of the surgical system. Prior telerobotic surgical systems with such pulley systems are described for example in U.S. application Ser. Nos. 08/517,053 and 11/314,040, the complete disclosures of which are incorporated herein by reference for all purposes.
Setting and maintaining cable tension is of prime importance for accurately and precisely moving the various apparatus and instruments during surgery. Previously, cable tension was set by screw clamps at the termination points of the cables. Setting the cable tension using these screw clamps required skill beyond that of standard field personnel.
What is needed, therefore, are improved apparatus and methods for setting cable tension in a telerobotic surgical system for remotely controlling surgical instruments at a surgical site on a patient. In particular, these apparatus and methods should allow for easily adjusting cable tension using standard tools. Accordingly, a cable tensioning apparatus, system, and method having improved efficiency and cost-effectiveness is highly desirable.